<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <ul class="nav">
      <li>我的首页</li>
      <li>产品介绍</li>
      <li>联系方式</li>
    </ul>
    <script>
      const nav = document.querySelector('.nav')
      console.log(nav)
      const li = document.querySelectorAll('ul li')
      console.log(li)
    </script>
  </body>
</html>
